PURIFICATION OF KYZYLKUM WET PROCESS PHOSPHORIC ACID AND CONCENTRATED BRANDS OF MONOAMMONIUM PHOSPHATE BASED ON IT

In this work, the processes of purification of wet process phosphoric acid of Kyzylkum phosphorite and the obtaining of mono- and diammonium phosphates (MAP and DAP) were studied. It was shown that at a 125% norm of CaCO3, the degree of removal of sulfate ions is 85.65%. The resulting gypsum sludge contains (wt.%): P2O5 – 22.12, CaO– 24.21, MgO– 4.69, Fe2O3– 0.27, A12O3– 0,50, SO3– 32,01, F – 0,53 and is proposed as superphosphate slow release action. When neutralized with gaseous ammonia (pH = 4), the degree of purification of desulfurized acid from CaO; MgO; Fe2O3; Al2O3 and F are provided at 87.69; 48.53; 98.56; 94.46 and 65.13%, respectively. Due to the high concentration of phosphorus (at least 38% P2O5total and P2O5total: P2O5total = 80%) and nitrogen (more than 7% N), the sediment is an independent nitrogen-phosphorus fertilizer - ammophos. Doammonization of the purified slurry to pH = 5.5 and 8.5 formed the basis for the preparation of MAP and DAP grades P2O5: N = 52: 14 and 48: 18, respectively. X-ray diffraction analysis shows that MAP consists of dihydroorthophosphate, and DAP consists of ammonium hydroorthophosphate.